This invention relates to an ozone generator cell and more particularly to a compact ozone generator cell having improved production efficiency.
Ozone is an excellent oxidizing agent. Not only has it high oxidizing power but its presence is readily detectable by its odor even at very low concentrations. For these reasons, demands for ozone are increasing in all fields of application including the thin film deposition of oxide onto silicon wafers.
Ozone is produced by passing dry air or oxygen through a high-frequency electric field. An ozone generator according to a typical design includes an internally cooled cylindrical electrode disposed inside and surrounded by a tubular electrode in coaxial relationship therewith. As the gas is passed axially through the annular space created between the electrodes, it is subjected to a high-intensity corona discharge and a portion of the oxygen in the gas is converted to ozone in the same manner in which ozone is generated in the atmosphere by lightening.
Recently, Masuda, et al. disclosed in a conference report a ceramic-based ozone generator consisting of a tubular cylinder with an inner alumina layer of thickness about 0.5 mm whch is sandwiched between discharge electrodes on the inner surface and a planar induction electrode on the outer surface and is further surrounded by an outer ceramic layer adapted to provide mechanical strength. Ozone generators of this type are now available from Shimon Kabushiki Kaisha of Tokyo, Japan.
Although these ceramic-based ozone generators seem to be able to generate ozone more efficiently than the conventional generators with concentric cylindrical electrodes, it is technologically difficult to manufacture the ceramic components required therefor. Moreover, the cooling of the ceramic components by running water does not seem sufficiently efficient and there is the serious problem of mechanical reliability because of ceramic cracks and water leaks into the ozone line.